The present invention generally relates to the transportation of heavy columnar construction members, including oilfield tubing, casing, drill pipe, drill collars, line pipe, columnar piles and similar materials. The present invention more specifically relates to various embodiments of an apparatus and a method for securing such heavy columnar members, and facilitating the loading and unloading of such heavy columnar members from the transporting conveyance, typically a flat-bed trailer, but also including the deck of a supply boat, or other conveyance. While the disclosed apparatus and method have application in transporting other types of heavy columnar members, the apparatus and method have direct application to the transporting of oil tubulars, including tubing, casing, drill pipe, drill collars, line pipe, etc., which are hereinafter collectively referred to as “tubulars”. The tubulars are utilized in the drilling, completion and production of oil and gas wells from both onshore and offshore locations.
Various sizes of tubulars are utilized in drilling, completion and production operations, usually ranging from diameters of 2⅜ inch to 24 inches or larger. These tubulars are typically in lengths of 31 feet and are manufactured from carbon steel and various alloys, and thus can be extremely heavy. The tubulars typically have threaded ends and couplings. Because the integrity of the threaded connections is critical, many different services are encountered, there are a variety of different threads which may be utilized on the tubulars, many of which are very expensive and which are easily damaged if handled incorrectly. Therefore transporting tubulars in a manner safe for both personnel and equipment can be challenging.
The handling of long and heavy tubulars utilized used in oil drilling, completion and production operations presents difficult problems and potential hazards to the persons involved in manipulating the tubulars and potential damage to property which may occur if the load comes loose or shifts during loading, transportation, or unloading. The tubulars may also be damaged, resulting in a substantial loss. Exotic materials may be required because of the hostile environments which may be encountered in the well, including acid-forming gases such as hydrogen sulfide and carbon dioxide. The tubulars may also comprise various coatings which are utilized for corrosion and/or wear resistance.
Oilfield tubulars are heavy, difficult to handle because of the weight, length, and shape, and are relatively expensive. Unfortunately, because oilfield tubulars are heavy and usually metallic, these items are often viewed by handling personnel as virtually indestructible. However the tubulars are not immune to damage from handling abuse. For example, threads can be damaged from impact with other tubulars, pipe racks, or the ground. Dents in tubulars can cause stress risers which can adversely impact the integrity of the material because of stress fatigue and/or impacting the corrosion resistance of the material, or damage the protective coatings used on the material. Because the tubulars are heavy, it can be very cumbersome and dangerous to move joints of pipe back and forth between the trailer and the pipe rack and/or rig floor.
Tubulars are frequently delivered to onshore well locations with flatbed pipe trailers. The pipe trailer typically has upright members on each side of the trailer which retain the tubulars within the trailer. The rows of pipe are separated by wood strips, typically 4×4 pieces of lumber. Additionally, chalks are nailed to the ends of each wood strip tubulars such that a chalk member is placed against the sides of the outside tubulars on the wood strip. The chalks prevent rolling and shifting of the load of pipe as it is being hauled. The tubulars are usually loaded on the trailer with a fork lift and off-loaded at the well site with slings which are attached to a line from a crane. In order to attach the slings to the pipe, it is necessary to wrap the sling around the pipe.
However, transporting tubulars with the known pipe trailers and utilizing the above procedure has several drawbacks. The entire load of pipe, which can weigh as much as 50,000 pounds or more, is contained by as few as four upright members on the outside edges of the flatbed trailer. An unplanned, and dangerous, release of pipe from the trailer can occur. For example, if the chalks on the outside of the pipe are knocked loose by shifting tubulars as the trailer goes around a turn, the entire load of pipe may impact the upright, potentially resulting in injury to persons and property, including damaging the pipe itself.
The known apparatus and method have additional disadvantages. For example, the process of installing the chalks can be time consuming as chalks are nailed down and are placed around the outside pieces of pipe of each row. Offloading the pipe can be time consuming and dangerous as well. Wrapping slings around the pipe requires the slings to be threaded around joints of tubulars. In order to thread a sling around the joints, the joints often need to be moved with pry bars in order to grasp an end of the sling as it is wrapped around the joint. Another problem is determining whether the weight of the tubulars has exceeded the load capacity of the trailer. An overloaded trailer presents a hazard to life and property.
For the above reasons, an alternative retaining system, also referred to as an adjustable pipe bunk, is disclosed herein.